Flowers. - Yellow, large, two and a half to three and a half inches across. Calyx. - Of numerous sepals. Corolla. - Of ten or twelve petals. Stamens. - Numerous. Pistil. - One, with numerous stigmas. Fruit. - Shaped like a small pear, often with prickles over its surface.

This curious looking plant is one of the only two representatives of the Cactus family in the Northeastern States. It has deep green, fleshy, prickly, rounded joints and large yellow flowers, which are often conspicuous in summer in dry, sandy places along the coast.

O. vulgaris, the only other species found in Northeastern America, has somewhat smaller flowers, but otherwise so closely resembles O. Rafinesquii as to make it difficult to distinguish between the two.